Circumferential pipe cutting or welding machine



Nov. 20, 1934. J, 1.. ANDERSON 1,931,341

CIRCUMFERENTIAL PIPE CUTTING OR WELDING MACHINE Filed July 1, 1953'ATTdRNEY Patented Nov. 20, 1934 CIRCUMFERENTIAL PIPE CUTTING OB WELDINGMACHINE James L. Anderson, Closter, N. J., assignor to Air ReductionCompany, Incorporated, New York, N. Y., a corporation of New YorkApplication July 1, 1933, Serial No. 678,609

9 Claims.

This invention relates to circumferential pipe cutting or weldingmachines of the type having a torch carriage movable on and around thesurface of a pipe and held against the pipe by 5 a sprocket chain orother flexible member which passes around the pipe and over thecarriage. A machine of this kind is shown in my copending applicationSerial No. 628,664, filed August 13, 1932.

[ When operating such machines, the relative movement of the carriageand pipe can be caused by moving the carriage, or turning the pipe withrespect to the carriage, or both. The carriage is ordinarily equippedwith a mechanl ical driving mechanism, and it is mportant that thedriving mechanism move the carriage over the pipe surface at asubstantially uniform speed in order to obtain a smooth cut or weld.

As the carriage moves around the pipe it encounters variable resistance.When the relative movement is caused by turning the pipe with thecarriage stationary, uneven surface of the pipe or differences in thecurvature cause variations in the resistance to the. relative move-'ment of the carriage and pipe. The greatest variations, however, areencountered when the carriage is moved around a stationary pipe. Theweight of the carriage is an important factor in such operation, andadds greatly to the force required to move the carriage when climbing upthe side of the pipe. When the carriage is go-' ing down the othersideof the pipe, its weight is usually more than enough to overcome theresistance to the carriage movement, and the I5 driving mechanism mustbe used to hold the carriage back and keep the speed down to the properrate for the cutting or welding torch.

There is some lost motion in the driving mechanism of a circumferentialpipe cutting or ,0 welding machine, and this lost motion tends toincrease somewhat with continued use of the machine. Variations in theresistance encountered by the carriage often cause the lost motion to betaken up first in one direction and 5 then in the other so that thespeed of the carriage is not uniform. This results in an uneven cut orweld, and sometimes leaves an uncut portion along the path of a cuttingtorch.

This invention has for its object to provide 0 an improvedcircumferential pipe cutting or welding machine of the type having aflexible member holding it against the pipe, and comprises novelfeatures and combinations of elements that reduce the variations in theresistance to the relative movement of the carriage and pipe and makethe carriage move uniformly at all times at the speed determined by thedriving mechanism regardless of lost motion in the driving mechanism.

Other objects, features and advantages of the invention will appear orbe pointed out as the description proceeds.

In the accompanying drawing, forming a part hereof:

Fig. 1 is a side elevation, partly broken away, show.ng acircumferential pipe cutting or welding machine embodying the invention,the machine being shown in position on a pipe:

Fig. 2 is a. reduced sectional view on the line 22 of Fig. I, with thetorch removed; and

Fig. 3 is an enlarged sectional view on theline 3-3 of Fig. 1.

-A torch carriage having a frame 10 is supported by rollers or wheels 12which contact with the outside surface of a pipe 14. The carriage isheld against the pipe by flexible members, as sprocket chains 16, eachof which passes around the pipe and over sprockets 18 and 20 (Fig. 2)supported by the carriage.

The sprocket 18 is secured to a drive shaft 22, which'is operated torotate the sprocket 18 and move the carriage around the pipe.

The drive shaft 22 is operated by handles 24 on. opposite ends of ashaft 26 carrying a worm gear 28 which meshes with a worm wheel 30 onthe drive shaft 22.

The sprocket 20 is an idler and is supported by a shaft .32, which ismovable away from the pipe 14 to control the tension of the sprocketchains. Means for thus tensioning the sprocket chains are described insaid copending application Serial No. 628,664.

A bar 34 fits within brackets 36 and is clamped in these brackets byscrews 38. The purpose of this bar is to support a torch at somedistance from the carriage. A clamp 40 is used to hold a torch 42(Fig. 1) for cutting or welding close to the carriage.

When. the carriage is moving up one side of the pipe, it is necessary totransmit enough force through the worm drive to overcome the resistanceadded by the weight of the carriage. As the carriage reaches the top ofthe pipe the force necessary to drive it decreases rapidly and 105 whenthe, carriage begins to go down on the other side of the pipe the weightof the carriage becomes an aid instead of a resistance to its movement.Some time in its travel across the top of the pipe, the play or lostmotion in the g worm drive will permit the carriage to move a shortdistance independently of the operating handles unless some precautionis taken to prevent such movement.

If there is substantial lost motion in the worm drive, the carriage maymove far enough to leave a part of the pipe uncut or not satisfactorilywelded, and even a slight movement ahead of the driving mechanism causesa rough place in the cut or weld.

By putting a brake on the drive shaft 22 with suflicient resistance torequire the transmission of some force through the worm drive mechanismat all times, even-when the carriage is going down the pipe, any lostmotion in the driving means can always be taken up in the same directionso that it has no effect on the movement of the machine. Such a brake isshown operating on the drive shaft 22.

A collar 50 is rigid with the drive shaft 22. A brake band 52, bestshown in Fig. 3, has a brake lining 54 in contact with the collar 50.

The friction of the brake is controlled by a screw 60 having a collar 62near its mid-portion and a square head- 64 for receiving a handle orwrench. The screw 60 extends through one side of the frame 10. Thecollar 62 abuts against the frame 10, and a nut 66 is threaded on theend of the screw 60 and clamped against the frame 10 to keep the screw60 from turning. The nut 66 is backed away from the frame 10 when thescrew 60 is to be turned to change the friction of the brake.

One end of the brake band 52 is anchored to the screw 60 against oneside of the collar 62, and the other end of the brake band is loopedaround a cylindrical nut 68 which is threaded on the screw 60. Turningthe screw 60 to the right draws the nut 68 toward the collar 62 andtightens the brake band around the drum so that the friction of thebrake is increased. Turning the screw 60 to the left moves the nut 68away from the collar 62 and loosens the brake.

There is enough resilience in the brake band and lining so that thefriction changes are gradual as the screw is turned one way or the otherto regulate the friction load on the shaft.

The friction of the brake should be great enough to hold the carriageback when descending the steepest' part of the pipe, and slightly morefriction than this is necessary for a factor of safety.

, Any greater friction than necessary increases the around the surfaceof the pipe, means comprising a flexible element adapted to be passedabout the pipe and in engagement with the carriage so as to hold thecarriage to the pipe, drive mechanism on the carriage for producingrelative circumferential feed between the carriage and the pipe, and afriction brake resisting the operation of said drive mechanism.

2. A circumferential pipe cutting or welding machine, comprising a torchcarriage adapted to travel on and around the surface of the pipe,

means comprising a flexible element adapted to be passed around the pipeand in engagement with the carriage so as to hold the carriage thereto,driving means on the carriage coacting with the flexible element toproduce relative circumferential feed between the carriage and the pipe,and a friction. brake resisting the operation of the driving means.

3. A circumferential pipe cutting or welding machine, comprising a torchcarriage having rolling supports to bear stably on the surface of thepipe, a sprocket wheel on the carriage, a friction brake resistingrotation of the sprocket wheel, a worm wheel connected with the sprocketwheel, a driving worm engaging the worm wheel, and a sprocket chainadapted to be passed about the sprocket wheel and the pipe.

4. A circumferential pipe cutting or welding machine, comprising a torchcarriage adapted to travel on and around the surface of the pipe, aflexible element adapted to be passed about the pipe and a portion ofthe carriage to hold the carriage to the pipe, driving means on thecarriage for producing relative circumferential movement of the carriageand the pipe, and friction brake means for resisting said relativemovement of the pipe and carriage.

5. A circumferential pipe cutting or welding apparatus, comprising astable carriage bearing .a torch, a flexible member for holding thecarriage to a round body, wheels rolling on the body and supporting thecarriage, a rotary member supported by the carriage and rolling on theflexible member, and a friction brake resisting riage against the pipe,a member on the carriage over which the flexible element passes, wheelssupporting the carriage for movement on and around the surface of thepipe, and friction brake means resisting such movement of the carriage.

7. A circumferential pipe cutting or welding machine, comprising a torchcarriage having rolling supports to bear stably on the surface of thepipe, a sprocket wheel on the carriage, a friction brake resistingrotation of the sprocket wheel, and a sprocket chain adapted to bepassed about the sprocket wheel and about the pipe so as to hold thecarriage to the pipe.

8. A torch apparatus for cutting or welding pipe, comprising a torchcarriage, a sling around the pipe and carriage for holding and guidingthe carriage on the pipe, wheels supporting the carriage on the pipe, aguide member on the carriage,-the sling passing over andcontacting withthe guide member to hold the carriage on the pipe, and friction brakemeans resisting relative movement of the carriage and the pipe.

9. A pipe cutting or welding machine including a torch carriage, rollerson the carriage for supporting it stably on the surface of a pipe, aflexible member for passing around the pipe and over the carriage tohold the carriage rollers against the pipe, a driving wheel on thecarriage engaging the under side of the flexible member, an idler wheelon the carriage engaging the under side of the flexible member, and afriction brake for resisting the rotation of one of said wheels.

JAMES L. ANDERSON.

